Battery charge programmers

ABSTRACT

The disclosure relates to Battery Charge Programmers which permit automatic charging of batteries by regulating the overcharge time of the battery being charged and which contain an overriding charge time limiter, to limit the total amount of time the battery is charged, independently of the state of charge.

O Unlted States Patent 1151 3,652,916 Ballman [451 Mar. 28,1972

[54] BATTERY CHARGE PROGRAMMERS 3,281,638 10/1966 Crawford "320/1310. 1ux 3,300,704 1/1967 McMi1len..... ....320/D1G. l UX [72] W Gm 3,217,22611/1965 Strain ..320/D1G1UX [73] Assigneez. Chargematic,lnc. 2,307,5761/1943 De Croce.. ..320/34 2,783,430 2/1957 Bower ..320/31 [221 FllediMay 28, 1970 3,453,519 7/1969 Hunter, Jr ..320/39 x [21] Appl. No.:41,423

' Primary Exammer-W1ll1am M. Shoop, Jr. Attorney-Joseph A. Fenlon,Jr.[52] U.S.Cl ....320/35, 320/40, 307/252F [51] ln1.C|. ..l-l02j 7/04 57ABSTRACT 8 Flld is h ..3 31;320 ,37, 9,4, [5 1 e 0 can 5 14 l -3 2; Thedisclosure relates to Battery Charge Programmers which permit automaticcharging of batteries by regulating the [56] References cued overchargetime of the battery being charged and which con- 1 tain an overridingcharge time limiter, to limit the total UNITED STATES PATENTS amount oftime the battery is charged, independently of the state of charge.3,217,225 11/1965 Gottl1eb etal. ..320/31UX Frezzolini ..320/49 X 6Claims, 2 Drawing Figures BATTERY CHARGE PROGRAMMERS This inventionrelates to Battery Charge Programmers.

In-present day battery charging operations, a need exists for a devicewhich will permit batteries to be charged automatically overnight, whileno superintending personnel are present. To prevent damage to thecharger in the event the battery will not accept a charge, the devicemust be capable of turning off the charger after a relatively fixedperiod of time after charging operations begin. To prevent damage to thebattery in the event the battery accepts the charge in a short period oftime, the device must be capable of turning off the charger within arelatively shorter period of time.

It is the object of this invention to provide a programmer which answersthe above described need.

With the above and other objects inview, which will become immediatelyapparent upon the reading of this specification, my invention resides inthe unique and novel form, arrangement, construction and combination ofthe various parts and elements hereinafter described and claimed.

IN THE DRAWINGS FIG. 1 is a schematic block diagram of a typical batterycharging system employing my invention; and

FIG. 2 is a detailed electrical schematic of the programmer comprisingmy invention.

Referring now in more detail, and by reference character to thedrawings, which illustrate a preferred embodiment of my invention, Adesignates a battery charging network comprising a source of externalpower P, which supplies power to a conventional battery charger througha relay 12 having two sets of normal open relay contacts 14,116, whichare closed by activation of a relay coil 18, all in the conventionalmanner; a battery 20 having a positive terminal 22 and a negativeterminal 24, which are respectively connected to charger outputterminals 26 and 28; and a programmer 30 which includes a pair ofvoltage sensing terminals 32, 34, respectively connected to the batteryterminals 22, 24, and also includes a pair of relay activation terminals36, 38, which are connected to the relay coil 18, all as shown in FIG.1.

Referring now to FIG. 2, the programmer 30 derives all of its operatingpower from the battery 20 being charged. Positive bias is applieddirectly to the unit from the battery terminal 22 through sensingterminal 32 and the common ground 40 is connected to the negativeterminal 24 through a blocking diode 42 and sensing terminal 34.

Connected between the sensing terminal 32 and the ground 40 are a relaycontrol network 44, a first voltage divider network 46, and a secondvoltage divider network 48. The first voltage divider network 46comprises four resistors 50, 52, 54 and 56a" connected in series. Thesecond voltage divider network 48 comprises a thermistor S8 and tworesistors, 60, 62, also connected in series. The relay control network44 comprises relay coil 18 which is connected to the collector 64 ofatransistor 66, having an emitter 68 connected to ground 40 and a base 70connected to the common connection of resistors 54 and 56.

Connected to the common connection of the resistors 50 and 52 on thefirst voltage divider network 46 is a Zener 72, and a resistor 74, theother end of the Zener 72 being connected to ground 40, and the otherend of the resistor 74 being connected to the gate lead 76 of a firstprogrammable unijunction transistor 78 (hereinafter referred to asP.U.T. 78), which also includes an anode 80 and a cathode 82. The anode80 is connected to the common connection of the resistors 60 and 62 inthe second voltage divider circuit 48, and the cathode 82 is connectedto ground 40 through two resistors 84, 86, in series. A first capacitor88 is connected between the anode 80 and the ground 40, a secondcapacitor 90 is connected between the gate lead 76 of the P.U.T. 78 andthe common connection of the resistors 52 and 54 in the first voltage,and a third capacitor 92 is connected between the common connection ofthe resistors 52 and 54 and the ground 40, all for purposes presentlymore fully to appear.

Also connected to the common connection of the resistors 52 and 54through a blocking diode 94 is the gate lead 96 of a second P.U.T. 98also having an anode 100 and a cathode 102. The cathode 102 is connecteddirectly to the ground 40.

The anode 100 is connected through a resistor 104 to the commonconnection of a resistor 106 (the other end of which is connected to thegate lead 76 of the P.U.T. 78), a blocking diode 108 (the other end ofwhich is connected to the common connection of the resistors 84 and 86),and a fourth capacitor 110, the other end of which is connected toground 40. A resistor 112 is also connected between the gate lead 96 andground 40.

It should be here noted that the operation of the invention, which willbe hereinafter described, is achieved by the unique characteristic ofthe P.U.T.'s to turn on at a precisely predetermined voltage.

The operation of the invention may be best understood by explaining theoperation when a weak battery 20 is connected across terminals 32, 34,for charging. When the battery 20 is connected, the voltage drops acrossthe resistors 52, 54, and 56 will be controlled by the Zener 72 and thetransistor 66 will go into conduction causing current to flow throughthe relay coil 18 actuating the relay 12. This causes operating power tobe supplied to the charger 10 from the source P and charging power to besupplied from the charger 10 to the battery 20.

As the battery 20 is charged, its terminal voltage will continue rising.The magnitude of the various components of the second voltage dividercircuit 48, including the thermistor 58 which compensates fortemperature variations, have been preselected to-establish a voltage atthe anode 80 which will turn on the P.U.T. 78 when the terminal voltageof battery 20 is at a level which indicates the battery 20 is fullycharged. At this point, both the P.U.T. 78 and the transistor 66 will bein simultaneous conduction, and the battery 20 will continue to chargeuntil the voltage across the capacitor 110 attains a predetermined levelwhich will cause the P.U.T. 98 to go into conduction. When the P.U.T. 98goes into conduction, the voltage drop across resistors 54 and'56 willdecrease substantially, the transistor 66 will go out of conduction, therelay coil 18 will deenergize, and power to the charger 10 will be cutoff, stopping the flow of charging current from the charger 10 to thebattery 20. Even with the charger l0 turned off, the power supplied bythe battery 20 will keep the P.U.T. 98 in conduction, once conductioncommences.

The operation of the P.U.T. 98 is controlled by two complementary, butindependent circuits, both of which determine the charge across thecapacitor 110. In the first circuit, the voltage across the zener 72will cause the capacitor 110 to charge through the resistors 74 and 106.Preferably the magnitudes of the resistor 106 and the capacitor 110 willbe selected to establish an RC time constant of at least several hoursduration. As the voltage across the capacitor 110 slowly increases, theP.U.T. 98 will gradually attain its turn-on voltage and conduction willcommence, independently of any other circuit. This first circuitprovides a protection override which will prevent a dead or extremelyweak battery 20 from being charged indefinitely.

The second circuit which affects the charge of the capacitor 110 is thecathode circuit of the P.U.T. 78 which includes the resistors 84 and 86.As the current flows through the resistors 84 and 86, the voltage dropacross the resistor 86 is applied to the capacitor 110 through the diode108. Although the voltage drop across resistor 86 should never reach theturn on voltage of P.U.T. 98, it should be apparent that the timerequired for the capacitor 110 to charge through the resistor 106 willbe greatly diminished by the transfer of the voltage through the diode108, which commences once the battery 20 reaches the fully chargedcondition, and increases as the battery 20 is overcharged. Bypreselecting the magnitudes of the resistors 84 and 86, the overchargetime can thus be regulated to a fixed period of time after the fullcharge condition.

As can be seen from the above, my invention provides a charger controlunit with regulated overcharge characteristics, and a protectiveoverride circuit which will limit total operating time of the charger.Since precise timing accuracy is not required, standard components maybe used.

It should be understood that changes, alterations and modifications inthe form, construction, arrangement and combination of the various partsmay be made and substituted for those herein shown and described withoutdeparting from the operation and principles of my invention.

Having thus described my invention, what 1 claim and desire to secure byLetters Patent is stated in the following claims:

1. A battery charge programming device for use with a battery chargerand a battery, said programming device comprising first voltage sensingmeans for automatically switching on the supply of charging current fromthe battery charger to the battery at the time a battery is connected tothe charging terminals of the charger, cutoff means for automaticallyswitching off the supply of charging current after the charging currenthas been switched on for a predetermined period of time, and a secondvoltage sensing means for reducing the amount of elapsed charging timebetween switching on and switching off if the battery becomes chargedprior to the elapse of the predetermined period oftime,

said first voltage sensing means including a first voltage dividernetwork operatively'connected to the charging terminals of the charger,semiconductor means operatively connected-to the charging terminals ofthe charger and to the first voltage divider network in such manner thatit will go into conduction when a battery is connected to the chargingterminals of the charger, and switching means for supplying chargingcurrent from the charger to the battery while the semiconductor means isin conduction,

said cutoff means including a first programmable unijunction transistorhaving a first anode, a first cathode and a first gate operativelyconnected to the first voltage divider network in such manner that asubstantially constant voltage exists between the first gate and thefirst cathode when the first transistor is not in conduction, and insuch further manner that the voltage existing between the first anodeandfirst cathode is determined by the amount of charge developed in a firstcapacitor, and first resistive means for gradually, over a predeterminedperiod of time, transferring from the first voltage divider network tothe first capacitor a voltage charge sufficient to place the firsttransistor in conduction,

and said semiconductor means being operatively connected to the firstvoltage divider network in such manner that when the first transistorgoes into conduction, the voltage supplied to the semiconductor from thefirst voltage divider network will be substantially reduced and thesemiconductor means will go out of conduction, thereby cutting off thesupply of charging current from the battery charger to the battery.

2. The device of claim 1 in which the first transistor is connected tothe first voltage divider network in such manner that said firsttransistor utilizes battery power to remain in conduction onceconduction has started.

3. The device of claim 1 wherein the second voltage sensing means asecond programmable unijunction transistor having a second gate, asecond anode and a second cathode, said second gate being connected to asubstantially constant voltage source, said second anode being connectedto a second voltage divider network which applies a certain percentageof the battery terminal voltage to the second anode, and said secondcathode being connected to a third voltage divider network which is alsoconnected, through a blocking diode to the first capacitor for purposesof transferring a voltage from the third voltage divider network to thefirst capacitor when the second transistor goes into conduction, therebyreducing the time required for the first capacitor to charge.

4. A battery charge programming device comprising:

a pair of sensing terminals;

first voltage responsive switching means for causing charging current toflow to a battery when said battery is connected across the sensingterminals; I 'Zener means for establishing a pomt of substantiallyconstant voltage above ground when said battery is connected across thesensing terminals;

a first programmable unijunction transistor including a first gate andalso including a first anode and a first cathode;

a first voltage divider network extending between the point of constantvoltage and ground and also being connected at an intermediate point tothe first gate;

a first capacitor connected at one end to the first anode through afirst resistor and connected at the other end to ground;

said first cathode being also connected to ground;

a second resistor of substantial magnitude connected to the ungroundedend of the first capacitor and to the point of constant voltage wherebythe first capacitor will slowly develop an increasing charge through thesecond resistor;

second voltage responsive means for deactivating the switching meansthereby causing charging current to stop flowing to the battery when thecharge across the first capacitor has attained sufficient magnitude tocause conduction in the first programable unijunction transistor;

and a second programmable unijunction transistor having a second gateand also having a second anode and a second cathode;

the second gate being connected to the point of constant voltage and thesecond cathode and the second anode being connected to the sensingterminals in such manner that the second programmable unijunctiontransistor will go into conduction when the terminal voltage of thebattery attains a predetermined magnitude;

and means for decreasing the amount of time necessary for the firstcapacitor to develop a charge sufficient to turn on the firstprogrammable unijunction transistor when the second programmableunijunction transistor is conducting.

5. The device of claim 4 wherein the means for decreasing the amount oftime necessary for the first capacitor to develop a charge comprises acathode resistor in the cathode circuit of the second transistor andcoupling means for transfering the potential across said cathoderesistor to the first capacitor.

6. The device of claim 5 wherein the cathode resistor is sized totransfer a potential to the first capacitor which is less than the turnon voltage of the first transistor, whereby the first capacitor willcontinue to charge while the second transistor is conducting, and thebattery will continue to be charged until such time as the firsttransistor goes into conduction.

1. A battery charge programming device for use with a battery chargerand a battery, said programming device comprising first voltage sensingmeans for automatically switching on the supply of charging current fromthe battery charger to the battery at the time a battery is connected tothe charging terminals of the charger, cutoff means for automaticallyswitching off the supply of charging current after the charging currenthas been switched on for a predetermined period of time, and a secondvoltage sensing means for reducing the amount of elapsed charging timebetween switching on and switching off if the battery becomes chargedprior to the elapse of the predetermined period of time, said firstvoltage sensing means including a first voltage divider networkoperatively connected to the charging terminals of the charger,semiconductor means operatively connected to the charging terminals ofthe charger and to the first voltage divider network in such manner thatit will go into conduction when a battery is connected to the chargingterminals of the charger, and switching means for supplying chargingcurrent from the charger to the battery while the semiconductor means isin conduction, said cutoff means including a first programmableunijunction transistor having a first anode, a first cathode and a firstgate operatively connected to the first voltage divider network in suchmanner that a substantially constant voltage exists between the firstgate and the first cathode when the first transistor is not inconduction, and in such further manner that the voltage existing betweenthe first anode and first cathode is determined by the amount of chargedeveloped in a first capacitor, and first resistive means for gradually,over a predetermined period of time, transferring from the first voltagedivider network to the first capacitor a voltage charge sufficient toplace the first transistor in conduction, and said semiconductor meansbeing operatively cOnnected to the first voltage divider network in suchmanner that when the first transistor goes into conduction, the voltagesupplied to the semiconductor from the first voltage divider networkwill be substantially reduced and the semiconductor means will go out ofconduction, thereby cutting off the supply of charging current from thebattery charger to the battery.
 2. The device of claim 1 in which thefirst transistor is connected to the first voltage divider network insuch manner that said first transistor utilizes battery power to remainin conduction once conduction has started.
 3. The device of claim 1wherein the second voltage sensing means a second programmableunijunction transistor having a second gate, a second anode and a secondcathode, said second gate being connected to a substantially constantvoltage source, said second anode being connected to a second voltagedivider network which applies a certain percentage of the batteryterminal voltage to the second anode, and said second cathode beingconnected to a third voltage divider network which is also connected,through a blocking diode to the first capacitor for purposes oftransferring a voltage from the third voltage divider network to thefirst capacitor when the second transistor goes into conduction, therebyreducing the time required for the first capacitor to charge.
 4. Abattery charge programming device comprising: a pair of sensingterminals; first voltage responsive switching means for causing chargingcurrent to flow to a battery when said battery is connected across thesensing terminals; Zener means for establishing a point of substantiallyconstant voltage above ground when said battery is connected across thesensing terminals; a first programmable unijunction transistor includinga first gate and also including a first anode and a first cathode; afirst voltage divider network extending between the point of constantvoltage and ground and also being connected at an intermediate point tothe first gate; a first capacitor connected at one end to the firstanode through a first resistor and connected at the other end to ground;said first cathode being also connected to ground; a second resistor ofsubstantial magnitude connected to the ungrounded end of the firstcapacitor and to the point of constant voltage whereby the firstcapacitor will slowly develop an increasing charge through the secondresistor; second voltage responsive means for deactivating the switchingmeans thereby causing charging current to stop flowing to the batterywhen the charge across the first capacitor has attained sufficientmagnitude to cause conduction in the first programable unijunctiontransistor; and a second programmable unijunction transistor having asecond gate and also having a second anode and a second cathode; thesecond gate being connected to the point of constant voltage and thesecond cathode and the second anode being connected to the sensingterminals in such manner that the second programmable unijunctiontransistor will go into conduction when the terminal voltage of thebattery attains a predetermined magnitude; and means for decreasing theamount of time necessary for the first capacitor to develop a chargesufficient to turn on the first programmable unijunction transistor whenthe second programmable unijunction transistor is conducting.
 5. Thedevice of claim 4 wherein the means for decreasing the amount of timenecessary for the first capacitor to develop a charge comprises acathode resistor in the cathode circuit of the second transistor andcoupling means for transfering the potential across said cathoderesistor to the first capacitor.
 6. The device of claim 5 wherein thecathode resistor is sized to transfer a potential to the first capacitorwhich is less than the turn on voltage of the first transistor, wherebythe first capacitor will continue to charge while the second transistoris condUcting, and the battery will continue to be charged until suchtime as the first transistor goes into conduction.